The oxidation of arylpropenes by 2,3-dlchloro-5,6-dicyanobenzoquinone (DDQ) has been studied, the objective being determination of the mechanism and scope of the reaction. Instantaneous molecular complex formation, attributed to the high electron affinity of DDQ, preceeded chemical reaction in all cases. The arylpropenes anethole and estragole, were oxidized to 2,3-dichloro-5,6-dicyanohydroqulnone bis(l-p-anisylpropenyl) ether (I) and 2,3-dichloro-5,6-dicyanohydroquinone mono(l-p-anisylpropenyl) ether (X), respectively. β-Methylstyrene was oxidized to 2,3-dichloro- 5,6-dicyanohydroquinone mono- and di-cinnamyl ethers (XII and XIII). α-Methyl styrene gave no reaction. Based on relative rate data, electron paramagnetic resonance results, and the nature of the reaction products, a hydride-ion abstraction reaction mechanism is proposed. In an analogous fashion the hydroquinone ethers underwent further oxidation by DDQ, leading to acetals, which rapidly hydrolyzed to p-methoxycinnamaldehyde or cinnamaldehyde. Ethers and X also underwent cleavage with hydrochloric acid and solvolysis with alcohol yielding p-methoxycinnamyl chloride and unknown I-(p-anisyl)-I-alkoxypropenes respectively. It is proposed that the latter form via a cyclic 5n2 1 mechanism. Finally, the arylpropenes are suggested to be slightly susceptible to charge-transfer polymerization by DDQ.

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